Wednesday, July 8, 2009

Fire, Can It Be Fitted Nasally?


Fire making is a complex process, as you know if you've ever tried to start one.

Harry Houdini said "That fire could be produced through friction finally came into the knowledge of man, but the early methods entailed much labor." No kidding.

This man had been around. If anyone knew, he did. If you don't think so then try rubbing things together and see what happens. Not much.

You will get bored, and tired, and blistered. To break the tedium try rubbing a balloon and sticking it onto the cat. You'll get excitement, heat without light, and some scratches. But no fire.

When you finally get fire it's because you did everything right. You need the atoms of one thing (fuel) excited enough to go and fight with atoms of another thing (oxygen). They get all mixed up, give each other lots of black eyes, and produce lots of heat and light. You want this. This is fire.

You need three things for fire: oxygen, fuel, and heat. This is true. Ask any firefighter. They know.

Luckily for us the atmosphere is 21% oxygen, and available worldwide, but things weren't always this convenient.

It took billion of years for disturbingly odd nameless blobs mucking around blindly to come up with the idea of oxygen at all. Then more millions and millions of years until they produced enough of it to matter, and it turned out to be toxic, killing most of them, but they kept at it, all so you could cook lunch.

So next time you see a wad of pulsing slime working away, churning out oxygen, how about a kind word? Maybe a kind word and a handful of granola? You can spare it.

OK, item two: fuel.

Fuel is what burns. Look around and you'll see plenty of it. For example, if you've ever set your pants on fire you've discovered fuel. Fuel is often the limiting resource in the fire equation, especially if you're wearing shorts.

Finally, the magical third ingredient, the hot stuff, heat. It starts things going and keeps them going.

So you have a fire, but the ideal, if you want a good, hot cup of coffee, is a controlled but self-sustaining fire. For this you need to be good at math, but not all that good. No adding or long division needed, just balancing this simple, three-element equation: heat plus oxygen plus fuel equals fire.

Or, if your higher faculties are more limited than that (possibly due to hunger, or because you're a backpacker) just remember that when you see wood and air and a flame you get a yummy cooked treat. Arf! Arf! Arf! Arf!

The theory of fire (there is such a thing), calls this "ignition continuity".

Here's how it works. Heat from the fire (the bright, wiggly, hot part that burns your paws) cycles back into the fuel and oxygen mix and keeps them hot enough to continue doing that thing that they do. Adults may know this as an "uninhibited chain reaction", but a full description is not available here.

Another interesting fact: solid fuel does not burn, and neither does liquid fuel. Only the whiffy, stinky, smelly stuff does. The whiffy, stinky, smelly stuff may be visible (smoke, from vaporized wood) or invisible (vaporized white gas, naptha, alcohol, benzin, kerosene, butane, or whatever you call it where you live).

Now, time for a quick review.

If you want a hot lunch you need oxygen, and fuel, and some kind of energy to kickstart things. Then when burning begins it throws off more heat, which keeps the process going. And this process continues until something runs out. Run out of fuel, or oxygen, or heat, and you're done. You need all three. So it pays to be quick with the weenies or you'll have to eat them cold.

Now you know why you can put out a fire by throwing water or sand on it (cuts off oxygen and cools it) or by pulling sticks out (removes the fuel). Or by taking off your pants (if you made a terrible mistake).

Of course there is more to it than this, and if you promise to be very, very good we may continue our story later some time.

Based on Fire In Your Hand
(paper)
(PDF)

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